Field of the Invention
The present invention relates to a technique for controlling an alternator; and, more particularly, to apparatus and method for variably controlling an alternator which mitigates idle booming and optimizes voltage control by variably adjusting responsiveness of the alternator based on conditions of an engine.
Description of Related Art
Generally, batteries are used as power supplies for vehicles. When a battery is used without being charged, it gradually deteriorates in performance. Therefore, there is the need for a battery to be charged rapidly during each use. A charging apparatus, in lieu of a battery, may be configured to supply current to other electronic device loads (an ignition device, headlamps, a radio, an air conditioner, etc.). An alternator is one of components of the charging apparatus. Typically, generator type alternators, which produce direct current using a commutator, have been used. However, recently, as the semiconductor technology continues to evolve, alternators which produce alternating current (AC) and convert the current into direct current using a diode have been used.
Generally, after a vehicle starts, the alternator is operated to supply electric energy required for the vehicle. A regulator maintains generation voltage of the alternator constant. In particular, generation is conducted based on a target generation value of an engine control unit (ECU). A generation rate signal of the alternator is transmitted to the ECU. Particularly, according to the settings of proportional integral control values in the regulator, the responsiveness is set to a fixed value.
Therefore, when the responsiveness is adjusted to be high, a problem of revolution per minute (RPM) oscillation may occur when idling. In other words, the range of fluctuation in generation rate with respect to external loads is excessively increased. Unlike this, when the responsiveness is adjusted to be low, a problem of voltage overshoot may be caused after full-load conditions are released. In other words, overvoltage conditions are caused, whereby controlling some components (e.g., CVVT control, purge control, etc.) may be interrupted, and failure diagnosis may become impossible.